This invention relates to a card-like electronic device such as an electronic card.
An electronic card generally comprises an intermediate frame such as a resin frame and a pair of covers such as metal covers attached to upper and lower surfaces of the intermediate frame. The electronic card is assembled by various known methods, for example, by adhering the metal covers to the upper and the lower surfaces of the intermediate frame by the use of a thermoplastic adhesive tape or a normal-temperature adhesion tape, by welding the metal covers on the upper and the lower surfaces, or by bonding the metal covers to the resin frame by ultrasonic welding. Further, there is also known a mechanical assembling method, for example, using a latch. In any event, no consideration has been made about disassembling of the electronic card after it is assembled.
At first, as a first conventional technique, description will be made of a method of assembling an IC card using an adhesive tape (for example, see Japanese Unexamined Patent Application Publication (JP-A) No. H06-320890). In this method, the IC card is assembled by sandwiching the adhesive tape between a frame and a cover. In this method, the adhesive tape must preliminarily be adhered to the frame or the cover. Therefore, an adhering operation is troublesome and an assembling cost and a material cost can not be suppressed. In case where a heat adhesive tape is used, a high-temperature pressure device is required in order to melt an adhesive. Further, a pressure cooling step is required in order to maintain an adhering effect. Accordingly, an expensive assembling apparatus and an increased working time are inevitably required. After completion of assembling of the IC card, an electrical problem or a mechanical damage in an exterior component such as a cover may sometimes occur. In this event, the IC card can not easily be disassembled because each component is firmly adhered by the adhesive. Even if the IC card can be disassembled, a mounting board or a connector as an internal component may possibly be damaged.
Next, as a second conventional technique, description will be made of a method of assembling a jacketed circuit card by welding (for example, see U.S. Pat. No. 5,529,503). In this method, upper and lower metal covers are attached to a frame by laser welding. This method requires an expensive laser welding apparatus. Further, it is generally impossible to disassemble the card.
As a third conventional technique, description will be made of a method of assembling a personal computer memory card by ultrasonic welding (for example, see Japanese Unexamined Patent Application Publication (JP-A) No. H8-241388). In this method, a first subassembly is produced by putting a first cover member into a first die and injection-molding a first frame member on the first cover member. Similarly, a second subassembly is produced by putting a second cover member into a second die and injection-molding a second frame member on a second die. Specifically, insert-molding is performed in a manner such that hooks of the first and the second cover members are embedded into legs of the first and the second frame members during injection-molding, respectively. The first and the second subassemblies are fixed to each other by ultrasonic welding. Then, the card is completed.
According to the third conventional technique, a resin molding apparatus is increased in scale. Since the above-mentioned molding operation is difficult, dimension control is troublesome. In addition, an expensive ultrasonic welding apparatus is required. Further, it is known that, when the first and the second cover members are applied with ultrasonic waves, electronic components mounted on an internal substrate may be adversely affected. Generally, it is impossible to disassemble the card after it is assembled.
As a fourth conventional technique, description will be made of a method of mechanically assembling a PC card (for example, see Japanese Unexamined Patent Application Publication (JP-A) No. 2000-322546). In this method, a top cover is provided with elastically deformable engaging protrusions formed on folding portions at opposite sides thereof. On the other hand, a bottom cover is provided with engaging grooves formed on folding portions at opposite sides thereof. By engaging the engaging protrusions with the engaging grooves, the top cover is attached to the bottom cover.
However, no consideration is made about disassembling of the PC card after it is assembled.